Expose Service Describer in Dart mojo package

mojo/dart/packages/mojo_services/lib/mojo/surfaces.mojom.dart

Index: mojo/dart/packages/mojo_services/lib/mojo/surfaces.mojom.dart
diff --git a/mojo/dart/packages/mojo_services/lib/mojo/surfaces.mojom.dart b/mojo/dart/packages/mojo_services/lib/mojo/surfaces.mojom.dart
index af735dd845a15370f18b6dbbc167fd54d81a22a5..7458edc2529f8b1a4c154eabcdbb1f4f1917a49b 100644
--- a/mojo/dart/packages/mojo_services/lib/mojo/surfaces.mojom.dart
+++ b/mojo/dart/packages/mojo_services/lib/mojo/surfaces.mojom.dart
@@ -1281,11 +1281,14 @@ const int _ResourceReturner_returnResourcesName = 0;
 
 
 class _ResourceReturnerServiceDescription implements service_describer.ServiceDescription {
-  dynamic getTopLevelInterface([Function responseFactory]) => null;
+  dynamic getTopLevelInterface([Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) => null;
+  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getAllTypeDefinitions([Function responseFactory]) => null;
+  dynamic getAllTypeDefinitions([Function responseFactory]) =>
+      responseFactory(null);
 }
 
 abstract class ResourceReturner {
@@ -1456,8 +1459,13 @@ class ResourceReturnerStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _ResourceReturnerServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _ResourceReturnerServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }
 
 const int _Surface_getIdNamespaceName = 0;
@@ -1469,11 +1477,14 @@ const int _Surface_destroySurfaceName = 4;
 
 
 class _SurfaceServiceDescription implements service_describer.ServiceDescription {
-  dynamic getTopLevelInterface([Function responseFactory]) => null;
+  dynamic getTopLevelInterface([Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) => null;
+  dynamic getTypeDefinition(String typeKey, [Function responseFactory]) =>
+      responseFactory(null);
 
-  dynamic getAllTypeDefinitions([Function responseFactory]) => null;
+  dynamic getAllTypeDefinitions([Function responseFactory]) =>
+      responseFactory(null);
 }
 
 abstract class Surface {
@@ -1787,8 +1798,13 @@ class SurfaceStub extends bindings.Stub {
 
   int get version => 0;
 
-  service_describer.ServiceDescription get serviceDescription =>
-    new _SurfaceServiceDescription();
+  static service_describer.ServiceDescription _cachedServiceDescription;
+  static service_describer.ServiceDescription get serviceDescription {
+    if (_cachedServiceDescription == null) {
+      _cachedServiceDescription = new _SurfaceServiceDescription();
+    }
+    return _cachedServiceDescription;
+  }
 }